Housewife L.C. Koh, 49, said she only noticed she could not make or receive calls last Thursday.

"I thought it was either the fault of my mobile phone or the SIM card. I kept rebooting the phone, then I put the SIM card into another phone. It didn't work," she said.

"I asked my sister to call me using her mobile. She's with another telco. The message she received was 'the subscriber's mobile phone is not available'," she said.

Another customer was told that the engineering department needed "seven to 10 working days to come back with the answer". The customer went on to say that one week later there has been no outcome or updates.

COMPLAINTS

This was a relevant concern as the number of homes with residential lines has fallen, according to figures released by Singapore's telecommunications sector regulator Infocomm Development Authority (IDA).

When approached, M1 said it had received feedback "from a number of mobile customers about network coverage in the Hougang Parkview area around mid-November".

Its director of Corporate Communications and Investor Relations Ivan Lim told TNP yesterday: "As part of our regular coverage enhancement programme, M1 was already working with HDB and the town council for the relevant approvals to install a new base station nearby."

He explained that M1 had started the site preparation and equipment was purchased for the new base station in August last year.

While the telco received "conditional in-principle approval from the authorities" last November, "we could only start installation works after full approval was received in August 2015".

"The installation works involve shutting down power to the entire block. This requires town council's coordination with residents of the block, which typically takes a fair amount of time.

"With new buildings and estates, network coverage for some residents can be affected at times. M1 constantly reviews our network coverage across Singapore to ensure we address such issues promptly," Mr Lim said.

The new base station at Hougang Parkview area is scheduled to go live by the end of next month, he said.

In the meantime, after TNP made queries, both Ms Ang and Mrs Koh said some semblance of service returned yesterday.